20989623 has 12 divisors (see below), whose sum is σ = 29538168. Its totient is φ = 13255920.

The previous prime is 20989613. The next prime is 20989627. The reversal of 20989623 is 32698902.

It is not a de Polignac number, because 20989623 - 2⁴ = 20989607 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20989627) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8608 + ... + 10773.

It is an arithmetic number, because the mean of its divisors is an integer number (2461514).

Almost surely, 2^20989623 is an apocalyptic number.

20989623 is a deficient number, since it is larger than the sum of its proper divisors (8548545).

20989623 is a wasteful number, since it uses less digits than its factorization.

20989623 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19422 (or 19403 counting only the distinct ones).

The product of its (nonzero) digits is 46656, while the sum is 39.

The square root of 20989623 is about 4581.4433315277. The cubic root of 20989623 is about 275.8469667284.

It can be divided in two parts, 20989 and 623, that added together give a palindrome (21612).

The spelling of 20989623 in words is "twenty million, nine hundred eighty-nine thousand, six hundred twenty-three".